Method of clearing tar accumulations from a coke-oven collector main



March 11, 1969 METHOD WATER COKE*OVEN COLLECTOR MAIN Filed July 7. 1966FL us/mva L/OUOR MAKE-UP RAW cox: ave/v 64.5 7 00 L 670/? 4mm L E 1 Zar- /waucr b RECOVER) FL USHHVG BATTERY 0/-' Jag 2 L/OUOR 00x5 ave-ms L,OUOR 0mm STRAI/VER 74/? k sgPA/m no/v v TAR CFEOSO 15%,2 G CREOSOTE80770415 STORAGE BOT-TOMS l4-A0UE0US AMMONIA INVENTORS HOME I? B.COLEMAN and ROBERT E. GARDNER,JL

Attorney United States Patent 3 Claims This invention relates to animproved method of clearing tar accumulations from a coke-oven collectormain A conventional battery of byproduct coke ovens includes a collectormain through which volatile matter and gases pass after their releasefrom the coal. The collector main is flushed continuously with flushingliquor, which is mainly aqueous ammonia. In this manner most tar iscarried from the main and recovered for further processing. Neverthelesssome heavy viscous tar accumulates in the main, and over a periodpartially clogs it. The usual practice is to clear out suchaccumulations manually with lances or like at approximately three-monthintervals. This operation is both time-consuming and hazardous andcauses air pollution.

An object of our invention is to provide an improved method of clearingtar accumulations from a collector main and avoiding the difficultiesusually encountered.

A more specific object is to provide a method of clearing taraccumulations from a collector main in which creosote bottoms recoveredfrom coal tar are added to the flushing liquor periodically as needed.

In the drawing:

The single figure is a diagrammatic layout of a cokeoven battery inwhich the collector main is cleared of accumulations by our method.

The figure shows a conventional coke-oven battery and collector main 12.The main receives volatile matter and gases released from the coal inthe coking process. A pump 13 continuously supplies flushing liquor froma vessel 14 to one end of the main. This liquor passes through aconventional strainer 15 between the pump and main. Tar and liquor fromthe main go to conventional tar separation equipment 16, from which theliquor returns to vessel 14. Tar from the separation equipment leavesthe system for further processing. Raw gas from the main goes tobyproduct recovery equipment 17. When make-up flushing liquor isrequired, water is added to the flushing system by opening a valve 18.Products from the byproduct recovery equipment 17 leave the system forfurther processing.

When a tar deposit accumulates in the main 12 to an extent that cleaningis required, we introduce creosote bottoms to the main via the flushingliquor. We obtain the creosote bottoms at the byproduct recoveryequipment 17. A pump 19 forces a stream of the creosote bottoms into theflushing liquor between the strainer 15 and main 12. The creosotebottoms have a boiling range (American Wood Preservers Associationdistillation) of about 290 to 355 C. (40 percent residue at 355 C.).They are at a temperature of about 190 to 210 F. or preferably about 200F. when we introduce them to the liquor. We include them in proportionsof about 0.5 to 0.8

percent by volume of the flushing liquor, or preferably about 0.75percent. During the cleaning operation we reduce the flushing liquorpump pressure from its normal level of about 44-45 p.s.i. to about 3638p.s.i. The pressure at the liquor sprays on the battery remains at thenormal 15 p.s.i. The liquor flow rate is approximately 1120 to 1250gallons per oven hour, or preferably about 1200 gallons. We add thecreosote bottoms continuously for a period of about 24 to 48 hours orpreferably approximately 32 hour, and at a rate of about 6.0 to 10.0 i

or preferably approximately 9.0 gallons per oven hour.

Although the creosote bottoms are not soluble in the flushing liquor,they are a solvent for tar which has accumulated in the main. Before onetest we inspected the main and found that it contained a large volume ofviscous tar. We introduced creosote bottoms according to the foregoingpreferred standards. We inspected the mains 24 hours later and foundthem completely free of tar, except for small quantities at the extremeends of the main. The tar at these locations was soft and easilyremoved.

While we have described only certain preferred ways of practicing ourinvention, it is apparent modifications may arise. Therefore we do notwish to be limited by the disclosure, but only by the scope of theappended claims.

We claim:

1. In a byproduct coking operation in which volatile matter and gasesrelease from coal pass through a collector main, and substantiallyaqueous ammonia flushing liquor is introduced continuously to said mainand carries away most of the tar, but some heavy viscous tar accumulatesin said main over a period, the combination therewith of a method ofclearing accumulations of tar from said main comprising introducingcreosote bottoms to the flushing liquor going into said main in anamount to provide about 0.5 to 0.8 percent by volume of creosote bottomsin the flushing liquor, the creosote bottoms being at a temperature ofabout to 210 F.

2. A combination as defined in claim 1 in which said creosote bottomshave a boiling range (American Wood Preservers Association distillation)of about 290 to 355 C. (40 percent residue at 355 C.)

3. A combination as defined in claim 1 in which the creosote bottoms areintroduced continuously over a period of 24 to 48 hours.

References Cited UNITED STATES PATENTS 167,755 9/1875 Fox 2012 1,556,24810/ 1925 Ohlwiler 13440 1,744,463 1/ 1930 Gravell 134-38 1,924,1638/1933 Miller 208-39 1,981,626 11/ 1934 McCloskey 208--39 FOREIGNPATENTS 10,573 5/ 1908 Great Britain.

1,343,981 10/ 1963 France.

NORMAN YUDKOFF, Primary Examiner. D. EDWARDS, Assistant Examiner.

US. Cl. X.R. 134-39; 202-241

1. IN A BYPRODUCT COKING OPERATION IN WHICH VOLATILE MATTER AND GASESRELEASE FROM COAL PASS THROUGH A COLLECTOR MAIN, AND SUBSTANTIALLYAQUEOUS AMMONIA FLUSHING LIQUOR IS INTRODUCED CONTINUOUSLY TO SAID MAINAND CARRIES AWAY MOST OF THE TAR, BUT SOME HEAVY VISCOUS TAR ACCUMULATESIN SAID MAIN OVER A PERIOD, THE COMBINATION THEREWITH OF A METHOD OFCLEARING ACCUMULATIONS OF TAR FROM SAID MAIN COMPRISING INTRODUCINGCREOSOTE BOTTOMS TO THE FLUSHING LIQUOR GOING INTO SAID MAIN IN ANAMOUNT TO PROVIDE ABOUT 0.5 TO 0.8 PERCENT BY VOLUME OF CREOSOTE BOTTOMSIN THE FLUSHING LIQUOR, THE CREOSOTE BOTTOMS BEING AT A TEMPERATURE OFABOUT 190 TO 210*F.